Ubuntu :: Can't Write On Webdav Mounted Drive

I use davfs2 to mount a Webdav drive at startup. It mounts correctly and I have read access to all files my account gives me access to. One big problem though: I can't create of modify any file. I know it is not a user account problem because everything works well when I mount the drive in Windows 7 using WebDrive.

Here's the entry in /etc/fstab to automatically mount the drive:

Code:
http://someserver.local/docs /home/my_user/km_docs davfs user,rw,auto 0 0

The Webdav is hosted on a local SAP Portal server (if anyone is familiar with this).

I also tried to use Cadaver. It connects and reads perfectly. But when I try to create a file, I get a "409 Conflict" error, even the file has never existed on the server before.